Wabben p



(No Model.) 7

W. P. FREEMAN.

TELEPHONE TRANSMITTER.

Patented Feb. 9} 1886.

Wiincncs.

W/fig Fhawuthn ra mr. Wahin tnn. D. C.

UNITED STATES PATENT Orrro a WARREN P. FREEMAN, OF NEW YORK, N. Y., ASSIGNOR TO BENJAMIN S. CLARK, OF SAME PLACE.

TELEPHONE TRANSMlTTER.

SPECIFICATION forming part of Letters Patent No. 335.806. dated February 9, 1886.

Application filed February 29, 1884. Serial No. 122,655. (No model.)

To aZZ whom it may concern.-

Be it known that I, WARREN P. FREEMAN, of the city, county, and State of New York, have invented certain new and useful Improvements in Telephone-Transmitters; and I hereby declare the following to be a full and clear description of the same.

This invention relates to an improved elastic cushion for the seat of the carbon electrode under the diaphragm-electrode, so as to produce a more delicate and elastic adjustment, and consequently a better articulation, than is now produced in electric telephones.

The invention will be readily understood by reference to the drawings, of which Figures l and 2 are sectional elevations of the improved instrument, taken in central vertical planes perpendicular to each other. Fig. 3 is a transverse sectional plan. Fig. 4 is a front elevation.

The case A of the instrument, with its conicallychambered mouth piece A, and diaphragm-B, are similar to those now in common use. The cushioned springs b b b are also similar to the corresponding parts in common use; and so, also, are the electrode or platinum point b the carbon conductor If, and its metallic base-plate b In my improved construction the said metallic baseplate b is secured, by soldering or otherwise, to the free end of a very delicate spring, 0, the fixed end of which is secured to the side of the case A or other convenient support. An elastic and flexible strap, D, is drawn across the instrument-case directly below and in contact with the bottom side of the spring 0, as is clearly shown in the drawings. The opposite ends of the said flexible strap or belt are coiled a few times around and secured, re spectively, to the frictionrollers D and D These rollers have suitable bearings at or near their ends, so as to allow them a slight rotation, but with sufficient frictional resistance to cause them to hold the band or strap D between them more or less taut, as may be desired. A conically pointed and seated setscrew at each end of each of the said rollers, as shown in the drawings, provides suitable bearings for this purpose. The band or strap piece Dis made of a piece of india-rubber band, or a ribbon of any suitable elastic textile fabric.

By turning one or both of rollers D D as desired, the band or strap D is drawn more or less tightly below the spring-seated carbon b, and the adjustment of the said carbon to the electrode 1) is thereby rendered exceedingly delicate and sensitive, and the articulation of the instrument is made very clear and distinct.

The induction-coil has an attached wire, F, leading to and attached to the diaphragm B. It also has an attached wire, G, leading to one pole of the local battery. A wire, H, connects one pole of the local battery with the metallic foot I) of the electrode If. The induction-coil E has also wire connections I and J, leading, respectively, to the telephone linewire and to the ground.

The metallic spring-arm G is set so as to throw a slight strain back upon the supporting belt or cushion D.

The rollers D D can easily be turned by the thumb and fingers, or by a suitable wrench, access to them being obtained by removing one of the sides of the wooden case. This is amply sufficient for the purpose, as the ad justment will not require to be of frequent occurrence, and will always be made by an expert adjuster.

It is obvious that when the band B is stretched perfectly tight the electrodes will be in their closest juxtaposition, and when the band is slack the electrodes will be more or less separated.

Having described my invention, I claim- 1. The elastic strap or band D, with its opposite ends attached to and wound around the friction-rollers D D, and its central part between the said rollers drawn under and resting against the metallic base of the central carbon electrode of a telephone-transmitter, in combination with said central elec trode, so as to adjust the said electrode to more or less proximity to the telephone-diaphragm by tightening or loosening the said band between the said rollers by turning one adjusted to more or less tension, so as to deli or both of them. cately adjust the position of the central elec- 1o 2. In a telephone-transmitter, a flexible trode. metallic spring 0 having one of its ends 5 fixed to the telephone-case, and the other at- WVARREN FREEMAN taehed to and supporting a central electrode, Witnesses: If, in combination with a transverse elastic G. SINELL,

strap or band, D, and means whereby it may be WV. I. DOUGHTY. 

